1. Field of the Invention
The present invention relates to a connection-type communication scheme as well as terminals and nodes used in such a connection-type communication scheme.
2. Description of the Related Art
As functions of a WWW (world-wide web) become ever more sophisticated, all sorts of information such as pictures, moving images, animations, audio data, music, etc., are exchanged through the Internet. Also, there are increases in broadcasting services based on one-to-many communications or downloading services allowing large-volume contents such as a new version of a software product to be downloaded via the Internet.
FIG. 1 is an illustrative drawing for explaining the Internet.
As shown in FIG. 1, when a client 1 in a country A requests a server 2 in a country B to transfer large-volume contents, intervening providers 3 and 4 in countries A and B, respectively, will have many communication lines thereof to be occupied by the transfer of these contents. This affects other communications.
In order to avoid this problem, satellite communication lines having a large capacity are employed to provide downlinks for the Internet. This reduces the load on the surface-system backbone, and, also, has been an effective force to facilitate new services for providing new types of large-volume contents.
FIG. 2 is an illustrative drawing showing use of a satellite communication line as a backbone between providers.
As shown in FIG. 2, data is transmitted from the country A to the country B via a surface communication line whereas data from the country B to the country A goes through the satellite communication line. Such routing is set in the provider""s routers. When a request for transfer of large-volume contents is sent from the country A to the server of the country B via the surface communication line, the requested contents are transferred to the provider of the country A via the satellite communication line. Accordingly, the surface communication lines between the provider 3 and the provider 4 are not affected in any manner by the transfer of large-volume contents.
FIG. 3 is an illustrative drawing showing use of a satellite communication line for connecting a provider to a client.
As shown in FIG. 3, a satellite communication line may be used for connecting a provider directly to a user. In this example, the provider""s routers are set such that data from the country A to the country B is sent via a surface communication line, and data from the country B to the country A is transferred via the satellite communication line. When a request for transfer of large-volume contents is sent from the country A to the server of the country B via the surface communication line, the requested contents are transferred directly to the client 1 in the country A via the satellite communication line. Accordingly, the surface communication lines between the provider 3 and the provider 4 are not affected in any manner by the transfer of large-volume contents.
ATM (asynchronous transfer mode) networks are used for providing large capacity communication lines.
When the provider""s routers are set such as to send data from the country B to the country A via a satellite communication line as shown in FIG. 2, small-volume contents, which need not be transferred via the satellite communication, ends up being transferred also via the satellite communication line. Such squandering use results in a shortage of communication capacities, which could have been used for large-volume data that are worth sending via a satellite communication line. Also, such squandering use results in limiting the number of users who can use such a service.
The configuration in which a provider is directly connected to the user via satellite communication as shown in FIG. 3 requires equipment for using a broadband communication line to be installed on the user side. Such equipment may be a parabola antenna or the like in the case of satellite communication. This increases the costs that the user has to bear.
FIG. 4 is an illustrative drawing showing a configuration which employs an ATM network in place of Internet providers.
As shown in FIG. 4, it will be likely in the future that a connection-type network such as an ATM network provides large-capacity lines in place of the Internet providers for the purpose of exchanging multimedia contents. Even in such a configuration, the same problems as described above will be observed.
Accordingly, there is a need for a connection-type network such as an ATM network which can make efficient use of bypass lines, and can save a user from the burden of excessive investment in equipment.
Accordingly, it is a general object of the present invention to provide a connection-type network scheme which can satisfy the need described above.
It is another and more specific object of the present invention to provide a connection-type network scheme which can make efficient use of bypass lines, and can save a user from the burden of excessive investment in equipment.
In order to achieve the above objects according to the present invention, a method of transferring data in a connection-type network in which nodes are connected via communication lines and terminals are connected to the nodes includes the steps of sending a request from a first one of the terminals to a second one of the terminals via a connection established on a first communication line, the request requesting transfer of data from the second one of the terminals to the first one of the terminals via a second communication line, establishing a connection on the second communication line between a first one of the nodes having the first one of the terminals attached thereto and a second one of the nodes having the second one of the terminals attached thereto, and transferring all or part of the data via the connection on the second communication line, wherein the second communication line is established to be in existence for a predetermined duration of time or for a time period during which said all or part of the data is transferred.
In this manner, data having a large size can be transferred via a broadband communication line without using the existing ordinary communication line in the connection-type network such as an ATM network, an ISDN network, a frame-relay network, etc. This achieves efficient use of a bypass line, and can save a user from the burden of excessive investment in equipment.
According to one aspect of the present invention, a terminal used in a connection-type network in which nodes are connected via communication lines and terminals are connected to the nodes includes a CPU, a memory storing a program therein for controlling said CPU, and an input/output unit, wherein said program comprises means for receiving a request from another terminal via an existing connection on a first communication line, the request requesting transfer of data to said another terminal via a second communication line, means for sending a message to a node connected to said input/output unit in response to the request, the message requesting for establishment of a connection on the second communication line between the node and one of the nodes connected to said another terminal, and means for transferring all or part of the data via the connection on the second communication line.
The terminal described above is suitable for use in the connection-type network according to the present invention, which achieves efficient use of a bypass line, and saves a user from the burden of excessive investment in equipment.
According to another aspect of the present invention, a node used in a connection-type network in which nodes are connected via communication lines and terminals are connected to the nodes includes a CPU, a memory storing a program therein for controlling said CPU, and a plurality of ports for providing connections, wherein said program comprises means for receiving an establishment message requesting establishment of a connection on a second communication line in addition to a connection on a first communication line already in existence between said node and another one of the nodes, and means for establishing the connection on the second communication line between said node and said another one of the nodes by using the second communication line.
The node described above is suitable for use in the connection-type network according to the present invention, which achieves efficient use of a bypass line, and saves a user from the burden of excessive investment in equipment.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.